13474-70-9Relevant academic research and scientific papers
Free Radical Reactions of Bicyclohexane and Bicycloheptane
Walton, John C.
, p. 1989 - 1994 (2007/10/02)
t-Butoxyl radicals abstract hydrogen from C(2) of bicyclohexane (3) to give bicyclohexan-2-yl radicals (6).At T>250 K radicals (6) rearrange by β-scission to cyclopent-3-enylmethyl radicals; both species were observed by e.p.r. spectroscopy.In spite of the much greater ring strain the activation energy for rearrangement of (6) is about the same as that of cyclobutylmethyl radicals.Bromine atoms abstract hydrogen from C(2) of (3), but bis(trimethylsilyl)aminyl radicals abstract the bridgehead methine hydrogen at C(1) as well as the methylene hydrogensat C(2).There is very little abstraction of the bridgehead hydrogen in bicycloheptane by bis(trimethylsilyl)aminyl radicals.Thus, the greater bridgehead reactivity of (3) as compared with the bridge positions is not simply due to the lower selectivity of the bis(trimethylsilyl)aminyl radicals, but is an intrinsic property of the bicycloalkane.
Electrolytic Reduction of 1,4-Dihalonorbornanes at Mercury Electrodes in Dimethylformamide. Evidence for Propellane as an Intermediate
Carroll, William F.,Peters, Dennis G.
, p. 4127 - 4134 (2007/10/02)
Low-temperature (-34 deg C) electrolytic reduction of 1,4-dibromonorbornane at mercury cathodes in dimethylformamide containing tetraalkylammonium perchlorates yields norbornane, bis(1-norbornyl)mercury, and 1,1'-binorbornyl; reduction of 1,4-diiodonorbornane results in the same three products along with 1-iodonorbornane and other minor species.At potentials for which the mass balance is 100percent, norbornane and bis(1-norbornyl)mercury account for 98percent of the electrolysis products and the coulometric n value is precisely three.When tetramethylammonium perchlorate is utilized as the supporting electrolyte at -34 deg C, there is a range of potentials over which a pronounced polarographic current minimun appears; this low-temperature minimum is attributed to adsorbtion upon the electrode of complex species consisting of tetramethylammonium cations and halide ions.Three key observations suggest that propellane is an intermediate in the electrochemical reduction of the 1,4-dihalonorbornanes: (1) norbornane is derived from 1,4-dihalonorbornane via a three-electron process which does not involve 1-halonorbornane as intermediate; (2) bis(1-norbornyl)mercury is produced by electrolytic reduction of 1,4-dihalonorbornane but not by reduction of 1-halonorbornane; and (3) a species apparently obtained by two-electron reduction of 1,4-dihalonorbornanes is capable of undergoing oligomerization.A polarographic wave seemingly attributable to reduction of propellane is observed.
Temperature Effects on the Selectivity of ?-Radicals
Giese, Bernd,Stellmach, Joachim
, p. 3294 - 3302 (2007/10/02)
Bent ?-radicals 3a-i, generated from alkylmercuric salts 1 and/or peresters 2, were treated with a BrCCl3/CCl4 competition system at different temperatures.Exner-analysis of these selectivity data (table 1) shows, that radicals of sp2 type 3a-d and bridgehead radicals 3e-i follow different isoselective relationships (figure 1, 2).Reversal of the selectivity row occurs at 310 and 210 K, respectively.Above of these isoselective temperatures less shielded radicals are more selective than more shielded radicals because entropy effects overcompensate enthalpy effects (table 2).Comparison with ?-radicals 6 shows, that each type of carbon radicals follows an isoselective relationship by its own.
